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21.
Beata Kosowska Sylwia Mozia Antoni W. Morawski Barbara Grzmil Magdalena Janus Kazimierz Kaucki 《Solar Energy Materials & Solar Cells》2005,88(3):269-280
The investigation on incorporating nitrogen group into titanium dioxide in order to obtain powdered visible light-active photocatalysts is presented. The industrial hydrated amorphous titanium dioxide (TiO2·xH2O) obtained directly from sulphate technology installation was modified by heat treatment at temperatures of 100–800 °C for 4 h in an ammonia atmosphere. The photocatalysts were characterized by UV–VIS–DR and XRD techniques. The UV–VIS–DR spectra of the modified catalysts exhibited an additional maximum in the VIS region (, ) which may be due to the presence of nitrogen in TiO2 structure. On the basis of XRD analysis it can be supposed that the presence of nitrogen does not have any influence on the transformation temperature of anatase to rutile. The photocatalytic activity of the modified photocatalysts was determined on the basis of decomposition rate of phenol and azo-dye (Reactive Red 198) under visible light irradiation. The highest rate of phenol degradation was obtained for catalysts calcinated at 700 °C (6.55%), and the highest rate of dye decomposition was found for catalysts calcinated at 500 and 600 °C (ca. 40–45%). The nitrogen doping during calcination under ammonia atmosphere is a very promising way of preparation of photocatalysts which could have a practical application in water treatment system under broader solar light spectrum. 相似文献
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Ye S Discher BM Strzalka J Xu T Wu SP Noy D Kuzmenko I Gog T Therien MJ Dutton PL Blasie JK 《Nano letters》2005,5(9):1658-1667
A family of four-helix bundle peptides were designed to be amphiphilic, possessing distinct hydrophilic and hydrophobic domains along the length of the bundle's exterior. This facilitates their vectorial insertion across a soft interface between polar and nonpolar media. Their design also now provides for selective incorporation of electron donor and acceptor cofactors within each domain. This allows translation of the designed intramolecular electron transfer along the bundle axis into a macroscopic charge separation across the interface. 相似文献
24.
Minoru Takeyama Jerzy Wojtowicz Kazimierz Butelski Eiji Watanabe 《Automation in Construction》2003,12(6):689-695
Computer dependent design space is illustrated with the recent international competition project for Kowloon Arts Center. The spatial condition of design resulted from the deployment of Euclidian geometry and use of the nonrational, complex surfaces. Another aspect of computer dependent space was rooted in the contemporary work situation where architects located on the three different continents collaborated in distributed mode over the internet. The resulting project confirms the creative potential of the above aspects of the digital space in contemporary design. 相似文献
25.
Antoni Drobnik Wiesław Jabłoński Kazimierz Rożniakowski 《Materials Research Bulletin》1978,13(8):731-735
The variation in the physical and chemical structure of the 6H13 alloy steel irradiated by laser light have been investigated. The phenomena of the capillary waves within the power density range (4.3×109<P<13.8×109) watt/m2 have been observed and the hydrodynamic parameters of alloy steel have been determinated. The nature of the laser light interaction with metal is discussed in electronmicroscopy and X-rays analysis terms. 相似文献
26.
The fractures of three model alloys, imitating by their chemical composition the matrixes of the quenched high-speed steels of various Mo: W relations were analyzed. According to the measurements of the stress intensity factor KIc and the differences in the precipitation processes of carbides it was found out that the higher fracture toughness of the matrix of the molybdenum high-speed steels than on the tungsten ones is the results of the differences in the kinetics of precipitation from the martensite matrix of these steels during tempering. After tempering at 250 and 650°C the percentage of the intergranular fracture increases with the increase of the relation of Mo to W in the model alloys of the high-speed steel matrix. This is probably the result of higher precipitation rate of the M3C carbide (at 250°C) and the MC and M6C carbides (at 650°C) in the privileged regions along the grain boundaries. The change of the character of the model alloy fractures after tempering at 450°C from the completely transgranular one in the tungsten alloy to the nearly completely intergranular one in the molybdenum alloy indicates that the coherent precipitation processes responsible for the secondary hardness effect in the tungsten matrix begin at a lower temperature than in the molybdenum matrix. After tempering for the maximum secondary hardness the matrix fractures of the high-speed steels reveal a transgranular character regardless the relation of Mo to W. The higher fracture toughness of the Mo matrix can be the result of the start of the coherent precipitation processes at a higher temperature and their intensity which can, respectively, influence the size of these precipitations, their shape and the degree of dispersion. The transgranular character of the fractures of the S 6-5-2 type high-speed steel in the whole range tempering temperatures results from the presence of the undissolved carbides which while cracking in the region of stress concentration can constitute flaws of critical size which form the path of easy cracking through the grains. The transgranular cracking of the matrix of the real high-speed steels does not change the adventageous influence of molybdenum upon their fracture toughness. On the other hand, the carbides, undissolved during austenitizing, whose size distribution in the molybdenum steels from the point of view of cracking mechanics seems to be unsatisfactory, influence significantly the fracture toughness of these steels. 相似文献
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Witold S. Kropacz Kazimierz Mikolajuk Andrzej Tobola 《International Journal of Circuit Theory and Applications》1984,12(4):375-393
This paper gives a new approach to the designing of power electronic networks. A method for the determination of passive time-varying networks is given when time functions of the excitation and response are given. These time functions are periodic. the period is divided into intervals. the network is linear and time-invariant in each interval. A sequence of the linear time-invariant networks is realized using switches. Switched windings of a multiport transformer are defined. Such elements enable one to realize the sequence of the linear time-invariant networks. Conditions for the substitution switches for thyristors are formulated. A structure of a thyristor converter is presented as an example. 相似文献
30.
Katarzyna A. Michalow Andre Heel Andri Vital Martin Amberg Giuseppino Fortunato Kazimierz Kowalski Thomas J. Graule Mieczyslaw Rekas 《Topics in Catalysis》2009,52(8):1051-1059
Effect of W doping as well as a thermal treatment on the structural and photocatalytic properties of TiO2 produced by flame spray synthesis (FSS) were the subject of investigation. Structural properties were studied by means of
X-ray diffraction (XRD), BET adsorption isotherm and transmission electron microscopy (TEM). The surface condition was investigated
by X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC) and differential thermal and thermogravimetric
analysis (DTA-TGA). The photocatalytic properties were studied by optical measurements and photodecomposition of methylene
blue under visible irradiation. It was found that the photoactivity in the visible region was enhanced significantly by the
W-doping as well as by additional thermal treatment of those nanopowders. The obtained TiO2-W nanopowders exhibited higher performance under visible light than P25. 相似文献